Background: Lumbar spondylolysis is a fatigue fracture of the pars interarticularis of the lumbar vertebrae. Lumbar spondylolysis occurs due to repetitive flexion, extension, and rotation of the lumbar spine, so it is not uncommon in swimmers, whose occurrence rate is approximately 2.3%. Since swimmers are known to have lower bone mineral density compared to other athletes, this may contribute to their heightened susceptibility to spondylolysis. Once a stress fracture has resulted in pseudarthrosis, it cannot heal with conservative treatment; therefore, healing can only be achieved through surgical means. Pseudarthrotic lumbar spondylolysis results in a pars defect, which requires surgical intervention to address intractable pain. Aim: To report a case of lumbar spondylolysis that progressed to pseudarthrosis and ultimately required surgical intervention. Methods: A 28-year-old male competitive freestyle sprint swimmer presented with recurrent low back pain. Computed tomography at the initial visit revealed defects of the pars interarticularis at the fifth lumbar vertebra with cortical sclerosis at the fracture interface, consistent with pseudarthrosis. Conservative treatment was ineffective, and surgical repair of the pars defect using the modified smiley face rod technique was performed. Results: Postoperative imaging demonstrated bony continuity at the previously separated segment, confirming successful bone union. Conclusions: The modified smiley face rod technique is a surgical procedure that preserves intersegmental mobility and is associated with a high rate of return to daily and sporting activities. It is considered an effective surgical option for relatively young patients with spondylolysis and minimal intervertebral disc degeneration. Bone union is typically achieved approximately one year after surgery, although careful intraoperative technique is required to optimize outcomes.
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